Gas tank install question

Okay, My trunk is all cut out while I installed my 4-link and I'm about ready to frame up a mustang tank. I've been searching through build threads to see how guys have been installing new tanks in their trunks. It seems like every build I see, guys build a frame for the tank and then add sheet metal to the tank frame and notch to build the trunk floor, essentially welding their body to the frame.

This sounds like a bad idea to me, but what do I know. Does anyone know why they do this and/or know of a build thread that shows this done differently?



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What kind of truck?,,lets see what your working with. HRP

 

Welding the body to the frame is a bad idea.

Gas tanks are usually strapped to the body. Mustang tanks drop through the trunk floor, the top surface becomes the trunk floor.

So, the tank mounts to the body. Use your own judgement here, but remember a full tank weighs about 150 pounds.

 

people do it that way because they are not too bright. I've even seen a "big name" local builder do it that way. to many people the only thing that matters is getting down to the ground.

there are more butchered trunks where the car will be filling with fumes while driving down the road on bagged cars than there are cars done right. over and over I see perfectly good trunk floors ripped out for no good reason... I don't get it.

working on a 51 Chevrolet right now that was all cut up and the 1 x 1" square tube frame for the gas tank and floor welded to the frame. the best thing to do would be to not cut out the floor in the first place other than where the frame kick up comes through.... too late for that now.

what we will be doing is cutting the new gas tank framework from the frame and mounting it on top of the frame with another body mount like the one that got removed during the notch process with rubber between the new trunk floor and frame rail.

how much of your stock trunk floor is missing?

 

It's a 53 Pontiac and pretty much my entire floor is cut out at this point. So yeah, too late now. It did make it easier for a newbie like me to work on it. I was trying to follow the lead of all these experienced builders on here until something didn't add up right.

49ratfink, what your talking about is kind of how I envision doing it. I'd love to see some pics of your work as you get it done.


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You do realize that Mustangs and every other unibody car around has the body welded to the frame don't you? It's a bad idea to weld the body to the frame if there are rubber body bushings, but if not it's done all the time by factories, and even more common in today's cars that are mostly unibody.

 

here is the piece of crap I started with. where the blue arrows are is where the square tube floor bracing was welded to the frame. rather than doing it like this guy did it, he should have made it a little higher and welded the other end of the tube to the inside fenderwell and ran it on top of the framerail with a rubber insulator to keep the noise down. make a body mount to replace the one that the notch eliminates.


look at the quality work the previous owners did. all that garbage is gone now. all I saved was the square tube frame for the tank.

 

Here's how I did mine in my '51 Henry J. It's part of the floor framework and not attached to the frame. The floor slopes to the back so the flange is inset to be level at ride height.

Blue

 

this is where I am now. if I had started with an original uncut car I would have done it completely different. it is not welded to the frame in these pics, and the braces from the hinges to the square tube are there just to hold everything in place.

the owner built the frame. I'm just putting a trunk back in it and a few other things.

basically I am going to continue the 1X1 tube over the frame one way or another with a bolt and a rubber mount in there like the rest of the body mounts. probably going to attach it to the inner fenderwell that is not there yet, I never finalize design details until I have an in depth conversation with my metal pile over in the corner....

 

I found a earlier picture. Not too far from where you are now.


Blue

 

Thanks Ratfink and Blue. So it sounds like there's two ways of doing this.

1. Weld the tank frame into the car frame. Then build the trunk sheet metal over the tank frame with rubber body mounts between the frame and sheetmetal. (How Ratfink is doing it, I think)

or

2. Weld the tank frame into the trunk/body sheetmetal and put rubber body mounts under the tank frame. (How Blue did it I think).

Right?

 

the tank frame is not welded to the car frame in my pics. when I am done the body will come off the frame just like stock. the floors and wheel tubs will be welded solid. everything will be sealed so if a person did a burnout the car will not be filling up with smoke.

the people who worked on this car before welded the trunk floor to the frame and all that is gone now.

show some pics of what yours looks like now.

 

Here she is (except shocks are installed now).

 

Any update on this build?? I'm finishing up same car. Looking for ideas on trunk

 

Not yet. Next weekend I plan on doing a little work. My buddy is coming out from Oregon who's also the general manager for Fuel Safe. He's bringing me a fuel bladder tank that is probably way overkill for this build.


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Thanks for straightening me out.